ESR study of thermal demagnetization processes in ferromagnetic nanoparticles with Curie temperatures between 40 and 60∘C

Thermal demagnetization in the vicinity of the Curie temperature of silver and sodium manganite nanoparticles, as well as copper–nickel and palladium–nickel alloy nanoparticles were studied by both static magnetic measurements and by electron spin resonance (ESR). ESR data indicate that some magnetic ordering remains even above the Curie temperature, determined by static magnetometry. Mechanisms of thermal demagnetization in alloy nanoparticles appear to be different from that in manganites.